1. Field of the Invention
The present invention relates to an article mounted to a support structure, more particularly to an article having a fastening insert for receiving a fastener to mount the article to the support structure.
2. Description of Related Art
As shown in FIG. 1, which illustrates a prior art thermoplastic structure 22, it is well known that sink marks 20 can occur on a surface of a thermoplastic structure 22. Sink marks 20 are distortions on the surface. The thermoplastic structures 22 with varying thickness profiles are prone to sink marks 20. The sink marks 20 are believed to occur in an area of increased thickness because the relatively large mass of thermoplastic material located in the area cools at a relatively slower rate as compared to the thinner portions of the thermoplastic structure 22.
A common method of attaching a thermoplastic structure 22 to a support source is to provide an attachment projection 24 within the thermoplastic structure 22. However, providing the attachment projection 24 results in the thermoplastic structure 22 having an area of increased thickness, and, as a result, sink marks 20 appear on the surface opposite the attachment projection 24.
Efforts to overcome sink marks 20 in thermoplastic structures 22 have been disclosed in the prior art. For example, decreasing a width of the attachment projection 24, relative to a thickness of the thermoplastic structure 22 has been shown to minimize sink marks 20. However, decreasing the width of the attachment projection 24 ultimately weakens the attachment projection 24. One strategy of reinforcing a weakened attachment projection 24 disclosed in the prior art consists of adding a wing element interconnecting the attachment projection 24 to the thermoplastic structure 22. However, the use of thinner attachment projections 24 in combination with the wing element approach increases the cost to manufacture the thermoplastic structure 22. The decreased width of the attachment projection 24 and the use of the wing element also limit the environments in which the thermoplastic structure 22 many be used for aesthetic reasons.
Another approach is to create a region which is void of material. Said differently, the interior of the thermoplastic structure 22 is hollow. The hollow interior reduces the thickness variation associated with the attachment projection 24 and is effective in eliminating sink marks 20. However, the hollow interior also has the undesirable consequence of weakening the attachment projection 24. The weakening of the attachment projection 24 limits the environments which the thermoplastic structure 22 many be used for structural reasons. Said differently, a strong attachment projection 24 is required in environments in which the thermoplastic structure 22 will be acted upon by an outside force. For example, as a handle for an appliance, such as a refrigerator or oven.
Inserts have also been placed inside thermoplastic structures 22 to eliminate sink marks 20. However, the use of such inserts has required an additional insulating layer between the insert and the thermoplastic structure 22. The presence of the insulating layer adds to costs associated with manufacturing the thermoplastic structure 22. Another consequence of the insulating layer is the presence of multiple material interfaces. Such interfaces can subject the thermoplastic structure 22 to torsional failure when the attachment projection 24 is engaged with a fastener.
Therefore, there remains an opportunity to develop an improved thermoplastic structure having a show surface free of sink marks while reducing cost and time to manufacture comprising an attachment projection which maintains a sink mark 20 free appearance while not imposing design limitations, increased costs, or structural weaknesses.